Railway traffic controlling apparatus



Dec. 17, 1940.

R. R. KEMMERER ETAL RAILWAY TRAFFIC CONTROLLING APPARATUS Filed April 19, 1939 THE/A 2 Sheets-Sheet l INVENTORS lZalphl-I'Jze menonand BY Cha 0 ZlZF'aZZO/ ATTO R N EY 'Dec. 17, 1940. R KEMMERER ErAL 2,225,118

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed April 19, 1939 2 Sheets-Sheet 2 m I a O O 5 \T mm, x v mm m a A! T 9 E M 6 56 mm m w m \m I R B wm R w l a N B 9.! ll Fallon.

BYU

THEIR ATTORN EY Patented Dec. 17, 1940 UNITED STATES RAILWAY TRAFFIC CONTROLLING APPARATUS Ralph E. Kemmerer, Swissvale, and Charles W. Failor, Forest Hills, Pa., assignors' to The Union Switch & Signal Company, Swissvale, Pas a corporation of Pennsylvania Application April 19, 1939, Serial No. 268,788

16 Glaims.

Our invention relates to railway traffic controlling apparatus and it has special reference to the organization of such apparatus into signaling systems of the class wherein coded trackway energy is utilized to control either or both Wayside signals and train carried cab signals.

One object of our invention is to provide a new and improved form of such organization which protects against the'giving of false proceed in dications in the event of breakdown of the insulated joints which electrically separate the rails of adjacent track sections.

Another object is to apply this protection to signaling systems which use code following track relays of the single element type.

An additional object is to effect the named protection without requiring that'devices at opposite ends of the automatic signal block be interconnected by line wires.

A further object is to extend the broken-down joint protection to all highway crossing signals which are within the limits of each of the blocks of the automatic Wayside system.

A still further object is to accomplish the above without dispensing with any of the desirable features of continuously coded track circuit control.

In practicing our invention we attain the above and other objects and advantages by: staggering the polarities of adjacent track circuits; supplementing each of the code following track relays of the automatic block system by an auxiliary track relay which responds only to rail energy of normal polarity; and arranging that each release of this auxiliary relay will cause the associated wayside and/r highway crossing signal to display a restrictive warning. Should, now, the coded energy from one track section leak forwardly over a defective joint into the rails of an adjacent section, this auxiliary relay immediately releases and causes the associated signal to indicate the faulty condition by a display of the above mentioned restrictive aspect.

We shall describe a few forms of railway traffic controlling apparatus embodying our invention, and shall then point out the novel features thereof in claims. These illustrative embodiments are disclosed in the accompanying drawings in which:

Figs. 1a and lb when placed end to end in the order named constitute a diagrammatic representation of a stretch of railway track which is equipped with traffic controlling apparatus embodying our invention;

Fig. 2 is a showing of filter-rectifier connections which are suitable for inclusion in the track relay supply circuits of Fig. l; a a

Fig. 3 is a partial representation of they high way crossing control circuits of Fig. 1a. supplemented to provide for two direction running, as in Fig. 1b;

Fig. 4 is a partial reproduction of 'one of the location equipments of Fig. 1 showing the. track and auxiliary relays thereof connected in paral-.. lel instead of in series; and Fig. 5 is a similar representation of corresponding apparatus modified to include a slowrelease auxiliary relay of the non-centrifugal type.

In the several views of the drawings like .ref-' erence characters designate corresponding .parts. Referring first to the composite diagram of Figs. 1a b, the improvements of our invention. are there disclosed as being incorporated in ;the trackway portion of a combined automatic block signaling and cab signaling system for a track l-Z over which it will be assumed that traffic moves in the single direction indicated by the arrows, or from left to right in the diagram. Insulated rail joints 3 divide the protected stretch of this track into the customary successive sections and the rails of each of these sections form a part of a track circuit of the usual character.

The particular track stretch which is represented in Figs. lab is intended for use in a railway system employing electric propulsion and for this reason alternating current track circuit energy is used together with impedance bonds 4 of the customary form which conduct propulsion current around each pair of the insulated. rail joints. As the description proceeds, however, it will become apparent that the apparatus of our invention is equally well suited for use on a steam road, in which application either direct current or alternating current track circuit energy may be used; in such an application, moreover, the bonds 4 would, of course, be omitted. H

In the composite diagram of Figs. la-b'only a single signal block D-E of the referred to automatic signaling system is completely shown. This particular block embraces two out locations Da and Db which are respectively occasioned by intersecting highways 6 and l and with which highway crossing protective signals XS are associated in the usual manner. Because of these two cuts the main signal block DE comprises three consecutive sections of track D--Da, Da-- Db and Db-E.

Positioned at the entrance of each of the main signal blocks (locations D, E, etc.) of the referred to automatic system is a wayside signal S,

illustratively shown as being of the color light type, which is adapted to indicate to an approaching train the nature of the trafilc conditions in the blocks immediately ahead. As signal Sd protects the entire block DE, no wayside signal is provided at either of the cut section locations Da or Db.

The rails of each of the referred to sections of track form a part of a track circuit to which coded alternating current train control energy normally is supplied through a track transformer TT connected with the rails at the traffic leaving or exit end of the section by means of a circuit which includes the usual current limiting reactor 8. This energy is derived from any suitable alternating current source and distributed to the several locations of track section division in conventional manner, as by the aid of a transmission circuit (not shown) extending along the right-of-way. In the diagram, characters B and C designate power distribution terminals which are supplied from one such source; to facilitate explanation, it will be assumed that the energy of thissource has a frequency of 100 cycles per second.

The particular signaling system shown in Fig. 1 is of the three indication variety and it makes use of track circuit energy of two different codings. These codings are produced by a code transmitter CT which interrupts the supply circuit of the associated track transformer T a definite number of times per minute according to the trafficor other conditions ahead. In the illustrative form shown, each device CT is provided with two circuit making and breaking contacts and I80 which are continuously actuated by a motor or other suitable mechanism (not shown in detail) at two different speeds. For purposes of explanation, it will be assumed that these speeds are such as respectively to provide codes of 80 and 180 energy pulses per minute.

Each of the referred to track circuits further includes the operating winding of a track relay TR which is installed at the traffic entering end of each track section and which receives operating energy from the rails thereof. Each of these track relays is of the single element code following type and may be designed to respond either to direct or to alternating current. When the relay is of the alternating current design, the winding thereof is directly connected to the rails of the associated track section in the manner represented at location E in Fig. lb; when, however, the relay is of the direct current design, this connection includes the resonant transformer unit shown at 9 at each of the diagram locations D, Da and Db. Typically, this unit 9 will include a transformer, a capacitor, a reactor and a rectifier connected as shown in Fig. 2 and so proportioned as freely to pass the cycle coded signal control energy which is received from the trackway and to rectify this energy before applying it to the relay winding.

In the illustrative automatic block signaling system of Figs. la-b, energy of one or the other of the previously described 88 and I80 codings is normally fed to the track circuits at all times and this coded energy is used to controlboth the Wayside signals and cab signals mounted on a train which proceeds along the track I--2. Because of the well-known character of such cab signals, no attempt has been made to disclose them in the present application.

The aspect that is displayed by the wayside signal S at the entrance of each of the main signal blocks is determined by a pair of decoding relays DB5 and DRI8I3 installed at each signal location in conventional manner. Relay DRIBO is a code distinguishing device while relay DRI-I functions to detect the presence or absence of code following operation by track relay TR. Ln addition to controlling the associated Wayside signaL each of the code detecting relays DRH also selects the coding of the energy which is supplied to the rails of the track section to the rear of the signal.

In the illustrative arrangement which we have shown, both of the decoding relays DRH and DRI80 receive their energizing current from the secondary Winding of a decoding transformer DT. This transformer is represented as being of conventional design and as having a primary energizing circuit that is pole changed in customary manner by a contact E2 of the code following track relay TR. Each time that this contact is picked up, direct current flows in one direction through one portion of the transformer primary (by way of a circuit which extends from the positive terminal of a suitable supply source through front contact I2, conductor I4, the right half of the transformer winding and mid tap I5 back to the negative terminal of the supply source) and each time that contact I2 is released, the current flows in the opposite direction through another portion of the winding (by way of a circuit which includes conductor I5 and the left winding half).

'The resulting alternating current voltage of code pulse frequency which is induced in the secondary winding of transformer DT supplies the winding of code detecting relay DRH with current of pick-up intensity whenever the associated track relay TR follows either of the 80 or I80 trackway codes. Included in the supply circuit of this relay is a rectifier unit DU80 which permits current passage at either of the code pulse frequencies named, and thus renders the relay responsive to both of the two codes.

In consequence, this code detecting relay DRH picks up whenever the associated track relay 'I'R follows either of the 80 or I 8i) trackway codes.

The code distinguishing relay DRIBI], however, is arranged to pick up only when the received code is of the I80 energy pulse per minute variety and for effecting this selective response the energizing circuit for relay DRISB includes a tuned unit DUI8ll which passes current of pick up intensity to the winding of that relay only when the frequency of the decoding transformer output voltage is of the I80 code rate. of the well-known character of such tuned units, no detailed description thereof is here given.

The aspect displayed by the associated wayside signal S is determined by a contact I3 of the code detecting relay DRI-I acting in cooperation with a contact I9 of the code distinguishing relay DRIED. In the event that the track relay TR fails to respond to coded energy from the trackway, the contacts of both decoding relays will remain released and under this condition (which is in effect when the guarded track section is occupied by a train) the controlled wayside signal S displays the indication of stop by virtue of lamp R thereof receiving lighting current over a circuit extending from the positive terminal of a suitable supply source through back contact I8 of relay DRH, conductor 2I and the lamp R back to the negative terminal of the supply source.

When, however, energy of the low speed or 80 Because pulse per minute coding is received and responded to by the track relay TR, code detecting relay DRH picks up and under this condition the controlled wayside signal S displays the approach indication by virtue of lamp Y thereof receiving lighting current over a circuit that extends from the positive supply terminal through front contact 18 of relay DRH, back contact H! of relay DRiBil, conductor 22 and the lamp Y back to the negative supply terminal. Finally, when energy of the 180 pulse per minute coding is received from the trackway, both of the relays DRH and DRESD pick up their contacts and the controlled wayside signal S then displays the clear indication by virtue of lamp G thereof receiving lighting current over a circuit which may be traced from the positive supply terminal through front contact l8 of relay DRH, front contact IQ of relay DRI80, conductor 23 and the lamp G back to the negative supply terminal.

In selecting the coding of the energy which is supplied to the rails of the track section to the rear of each of the wayside signals, the code detecting relay at each of the locations D, E, etc. makes use of a contact 24 which is included in the supply circuit for the section to the rear of that location. Depending upon whether this contact ispicked up or released. the primary winding of the associated track transformer TT is periodically connected with the alternating current source B-C over one or the other of coding contacts I80 and 80 of device CT.

The former condition is in effect when a train occupies the advance section of track and releases both the track relay TR and the code detecting relay DRH at the entrance end thereof; under that former condition the rails of the rear track section receive energy of the 80 pulse per minute coding over a circuit which may be traced from the supply terminal B through the coding contact 80 of device CT, conductor 25, back contact 24 of relay DRH, conductor 26 and theprimary of the track transformer T1 back to the supply terminal C.

The latter condition is in effect when energy of either the 80 or the 180 pulse per minute coding is received and responded to by the track relay TR; in that event the code detecting relay DRH is held continuously picked up and the rails of the rear track section then receive energy of the 180 pulse per minute coding over a circuit which may be traced from the supply terminal B through the coding contact 180 of device CT, conductor 2'8, front contact 24 of relay DRH, conductor 26 and the primary of track transformer TT back to supply terminal C.

From the foregoing it will be seen that the illustrative organization of apparatus which is in cluded in the composite diagram of Figs. 1a-ZJ constitutes the trackway portions of a three indication combined automatic block signaling and. cab signaling system which operates in conventional manner.

As will be explained more in detail presently,

' the equipment at each of the two cut section locations Da and Db is arranged to repeat intothe rails of the section to the rear of the locations the pulses of coded energy which are received from the rails of the section ahead of the location and in this manner the pulses of coded energy which are supplied through the rearwardly extending rails at the exit end B of the main signal block DE are transmitted around the in sulated joints 3 at each of the two out section 10- cations and thence over the rails ahead of the entrance end D of the signal'block to the track relay TR at that entrance location. The just referred to conventional operation of the automatic block signaling system herein disclosed applies, therefore, whenthe system is used with signal blocks which both do and do not contain out sectio-ns.

The illustrative organization of the represented coded system of automatic block signaling having been described, attention will now be directed to the herein disclosed facilities for protecting against the giving of false proceed indications in the event of breakdown of the insulated joints 3 which electrically separate the rails of adjacent sections of the signaled stretch of track.

Such a joint failure is hazardous in that its usual effect is to cause the wayside signal S at the location of the fault'to give a proceed indication even though a train may occupy the track block which the signal guards. Assume, for example, that the .joints 3 at loca'tion D break down upon the passage of a train through the block DE of the diagram of Figs. la-b. This permits energy of the 80 coding to feed over the faulty joints from the rear section rails into the rails of the occupied forward section and as soon as the rear of the train passes some distance beyond the point of connection of the winding of track relay TR with the rails of this forward section, the potential between these rails (resulting from the rear section leakage energy) rises to a point sufficient to effect code following operation on the part of relay'TR. Acting in the normal manner through the associated decoding relays DRH and D Rl80, this causes the control wayside signal Sd to display the yellow or approach indication. w H V Were the leakageenergy allowed, as in the past,

'to persist in influencing the decoding apparatus,

it would transfer the feed-circuit for transformer T'I from the 80 coding contact to the I80 coding contact and that, in turn, would cause the energization of relay DRI80. This would cause the display of a clearf or green aspect by signal Sd and thereby falsely advise the engineman of a following train that the block DE is vacant when in reality it is occupied.

In the case of steam territory where the track rails I and 2 do not form'part of a propulsion circuit through which driving energy is supplied to electric locomotives, the conditions just stated result only in the event that both of the insulated joints 3 at'the signal location are defective simultaneously and thus interconnect rail l of the rear section with rail I of the forward section and rail 2 of the rear section with rail 2 of the forward section. In electrified territory, however, a single broken-down insulated joint 3 is the full equivalent of the just described two broken-down joints in steam road territory.

This is because of the auto-transformer action of the impedance bonds 4. Should, for example, the joint in rail I become defective and establish direct conduction from the rear section length to the forward section length of that rail, there is completed by the impedance bonds 4 a return path around the companion joint in rail 2 and this produces the same effect as were this second joint also to lose its insulating quality. In electrified territory, therefore, the probability of the false proceed signal indication previously discussed is comparatively high and requires special protection facilities to prevent accidents and damage in the event of a broken-down rail joint. Inthe improved form of organization of our T mechanism 3 I.

invention, this protection is effected .at each signal location by staggering the polarities of adjacent track circuits, supplementing each of the code following track relays of the automatic block system by an auxiliary track relay CTR which responds only to rail energy of normal polarity, and arranging that each release of this auxiliary relay will cause'the associated signal to display a restrictive warning.

The staggering of the polarities of adjacent track circuits may, of course, be effected in any suitable manner. Conveniently, this result may be achieved by interposing the leads that connect the track transformer TT with the rails I and 2 at the exit end of the consecutive sections of track. In the particular arrangement shown, transformer T1 at the exit of section D-Da is so connected with the rails of that section that the right terminal of the transformer secondary is joined with rail I and the left terminal with rail 2; th transformer connection is reversed at the exit of section Da-Db so that there the right terminal of the transformer secondary is joined with rail 2 and. the left terminal with rail I; the connectionis made in the first named manner at the exit end of section DbE so that there the right terminal of the .transformer secondary is joined with rail I and the left terminal with rail 2; and so on.

Assuming that at a given instant the polarity of th right terminal is positive, the relative polarities of the rails of the several consecutive track sections will at that instant be as marked by the plus and minus signs in the composite diagram of Figs. lap-b That is, in section D-Da rail I will be positive and rail 2 negative, in section DoDb rail I will be negative and rail 2 positive, in section Db E rail I will be positive and rail 2 negative, and so on.

The auxiliary track relay CTR which supplements each of the code following track relays TR of the signaling system is connected to receive rail energy simultaneously with the device TR and may be of any suitable design which responds only to a received energy which has a polarity that is normal for the particular track circuit and which is sufliciently slow in releasing as to bridge the spacing between consecutive pulses of this received energy when it is coded at any of g the several rates of modulation that the signaling system employs.

As shown at each of the four locations in the composite diagram of Figs. lw-b; each of these auxiliary track relays is of the centrifugal frequency selective type. It is provided with a control winding 29 which receives trackway energy over a serial connection with the supply circuit for the code following device TR and also has a second or local winding 3!! which is arranged to receive energization from the alternating current source B-C over front contact II of the signaling system relay 'I-R. These two windings 29 and 313 form a part of an induction motor which opcrates the relay contacts by rotating a fly ball As long as this mechanism is at rest the contacts occupy their downward or .released positions; when, however, the device is rotated in a normal or forward direction the fly balls are moved outwardly by centrifugal action and this movement is utilized to raise the relay contacts.

To prevent the relay from responding to rail potential having an instantaneous polarity which is opposite to that of the current which the control winding 29 normally receives from the track rails, each of the auxiliary relays CTR is provided with means not shown) which make it unresponsive to reverse energization of any degree. Conveniently, such means may take the form of a ratchet device (not illustrated) associated with the mechanism 3I and arranged to permit the fly balls of that mechanism to be rotated only in the normal or forward (and not in the reverse) direction.

The contacts of each of the devices CTR reach their fully actuated or picked-up positions only when the speed of this rotation is of the high value which results when the relay windings are energized from the 100 cycle supply circuit BC. As any energy of the conventional cycle electric propulsion frequency which may accidentally enter the relay (as under unbalanced track circuit conditions) is incapable of producing the critical speed above referred to, false contact closure in electrified territory applications due to stray propulsion current thus becomes impossible.

As the description proceeds it will be apparent that instead of connecting the control winding 29 in series with the supply circuit for the code following track relay TR, this control winding of the auxiliary relay CTR may also be cGnnected in parallel with the named supply circuit. Such a parallel connection is shown in 4 and will be further discussed at a later point in this specification. Likewise, it will also become apparent that the auxiliary device need not in all cases be of the centrifugal frequency selective type which is illustrated'in Figs. 1 and 4 but may be of any suitable design which gives a polarized form of response and'is sufficiently slow in releasing as to bridge the spacing between consecutive pulses of the coded signal control energy which is received from the trackway. A second form of auxiliary relay having this characteristic is represented at CTRa, Fig. 5, and it also will be further described later.

Each of the auxiliary track relays CTR is so arranged that each release of its contacts will cause the associated wayside and/or highway crossing signal to display a restrictive warning. At each of the wayside signal locations D, E, etc. this arrangement takes the form of a contact 33 which is included in the primary exciting circuit for the decoding transformer D'I' at that location. As long as contact '33 occupies the represented picked-up position, this circuit is connected with the positive supply circuit over a front point of the contact; the code following track relay TR then causes the two decoding relays DRH and DRiBI] to control the wayside signal S in normal manner. When, however, the auxiliary relay CTR becomes released, this contact 33 opens the decoding transformer exciting circuit and thus causes both of the decoding relays DRI-I and DRI80 to go to the released positions regardless of whether the code following track relay TR may be responding to one or another of the 80 and 180 pulse per minute trackway codes. Under the condition just stated, the controlled wayside signal S displays the stop indication by virtue of contact I8 of relay DRH completing the lighting circuit for the red lamp R.

F,rom the foregoing it will be seen that as long as there is no failure of an insulated rail joint 3 the auxiliary or protective relay CTR does not alter the normal operation of 1 the coded system of automatic block signaling. Each of the code following track relays 'I'Rresponds to the received trackway energy in the same manner as were the control winding 29 of the auxiliary device not to be included in the supply circuit for the relay TR. That is, each pulse of coded energy which is transmittedover' the rails to the entrance end of the track section energizes both of the relays TR and CTR over a circuit which may be traced from the positive polarity rail (rail I in the case of each of sections D-Da and DbE and rail 2 in the case of section Da-Db) through conductor 34, the control-winding 29 of relay CTR, conductor 35, the winding of relay TR and conductor 36 back to the negative polarity rail (rail 2 in the case of each of sections DDa and Db-E and rail I in the case of section DaDb) Each time that the track relay TR picks up, contact II thereof completes for the local winding 30 of relay CTR an exciting circuit which may be traced from terminal'B of the 100 cycle alternating current source through front contact II, conductor 38 and the winding 30 back to terminal C of the alternating current source. In consequence, both of the windings 29 and 30 of the auxiliary relay CTR are simultaneously energized from source B-C during each pulse of the coded signal control energy which is received from the trackway. During, however, the intervals (oi'f code periods) which separate these received pulses, both of the windings 29 and 30 are simultaneously denergized; the supply .circuit for winding 29 then being interrupted by the coding contact 80 or I80 of device CT at the exit end of the signal block and the circuit for winding 30 being interrupted at contact II during each released condition of the code following track relay As long as the polarityof the energization of Winding 29 is of the normal character originally selected for the associatedtrack circuit, the code step recurringpulses of energy whichare applied to the windings 29 and 30 produce a normal direction rotation of the fly ball mechanism 3I which is sufficiently high in speedto bring the contacts of relay CTR into theirpicked-up positions and there maintainthem as long as coded energy continues to be received from the track circuit. The bridging of the off code periods is readily effected by the high rotative inertia of the fly ball mechanism 3 I which, in conventional designs of the centrifugal track relays, is sufficient to keep the rotor spinning freely for about two seconds after energy is removed from the: windings wand 30 before the front contacts of the relay open and for about two additional seconds after this time of opening .until the back. contacts of the relay are closed.

Contact 33 of relay CTR is thus maintained pickedup as long as relay TR at the same location continues to follow a signal control code during normal operation of the systemand under these conditions it connects the heel of the pole changing contact l2 with the positive terminal of the exciting source for the decoding transformer DT over a circuit which extends from that positive terminal through front contact 33 and conductor 39. As has already been pointed out;

track relays CTR further is such that these relays in no'way interfere with the response of the signaling equipment to the entry of atrai'n into and passage through the track sections of the signaled stretch. Under such conditions, the code following track relay TR is deenergized in the usual manner by the shunting action of the wheels and axles and both of the decoding relays DRH and DRI80 are released in the same manner as were the auxiliary relays CTR not to form a part of the signal location equipment. Under occupied conditions of the section, moreover, both of the windings 29 and 33 of this added device CTR are deenergized so that it releases its contacts. As the train leaves the section, the restoration of the coded energy to relay TR causes it to follow code in the usual manner and to relay CTR causes this device quickly to bring the fly ball mechanism 3 I up to normal speed and thereby pick up contact 33 and reconnect the pole changing circuit for the decoding transformer DT with the positive terminal of the exciting source.

In considering the manner in which the just described facilities prevent the giving of a false proceed signal indication in the event of a broken-down rail joint, assume that while passing over the joints 3 at location D of Fig. 1a a train causes either or both of them to break down and establish a'path over which energy from the rails of therear tracksection may feed into the rails of the forward section. This rear section energy is, as has been seen, of a polarity which is opposite to that of the forward section energy; accordingly, at the instant when rail I of the rear section is negative rail I of the forward section normally is positive and at the instant when rail 2 of the rear section is positive rail 2 of the forward section normally is negative.

Because of the presence of the train in the rear portion of the section D-Da, relay TRat location D is at first continuously deenergied, as is also the auxiliary relay CTR and, in consequence, the-contacts of both of the decoding relays DRH and DRI80 are dropped out in the normal manner tocause the controlled wayside signal Sd to display the stop or red indication which is appropriate for the occupied condition of the signal block of which location D marks the entrance. Under this condition, the rails of the section to the rear of location D are supplied with energy of the 80 coding over a circuit previously traced as including back contact 24 of relay DRH.

As soon as the rear of the before mentioned train has passed far enough beyond the signal location D to allow an on period of the 80 code energy (feeding from the rear to the forward section over the defective joint and the impedance bond return path) toenergize the track relay TR, the front contacts of this relay become picked up and contact II completes the exciting circuit over which the local winding 3fl of relay CTR receives normal polarity excitation. In the meantime, winding 29 of that relay is receiving the reversed polarity leakage energy from the rear track section. The path over which this leakage energy flows may be traced from the right terminal of transformer TT at location D through rail 2 of the rear track section, the defective rail joint 3, rail 2 of the forward section, conductor 36, the winding of relay TR, conductor 35, the Winding 29 of relay CTR, conductor 34,,rail I of the forward section, the sec-,

before and for this-reason the rotor mechanism cf the relay is urged .to rotate in the reversed direction. scribed ratchet device (not shown) which per- :mits'the fly balls tobe rotated only in the nor- .Because, however, of the before demai "or forward direction, "no movement of the mechanism 3| is possible and the'contacts-of the relay accordingly cannot be picked up by the -'-rear section energy which leaks over the dcfec'tiye rail joints.

In remaining in its released position, contact 33 of relay CT-R disconnects the'exciting circuit 'ofth'e decoding transformer DT from the direct current source. Even though, now, the signaling system track relay TR follows the coding of the rear section leakage energy, it is inefiective tor picking up either of relays DR'H and DR 'i80 and, as a result, the wayside signal S'd continues to display the-red or stop indication by virtue of the lighting circuit "for lamp R continuing to be completed over back contact l8 of relay DRH. This 's'top indication by the signal at the location of the defective joint continues uni-nterruptedly as the train advances entirely out of the track block and thus guards the section against -anunsaie entry by a following train.

When the rear of the departing train clears the exit 'end location E, coded signal control energy from that location once more is transmittedover the rails to the entrance end D. Here it may be so interfered with by the leakage energy fromthe-rear track section that relay TR cannot respond thereto in normal manner and in't'ha't-even't the stop aspect of the 'wayside signal 361 will continue until the brokendown joint is repaired. In the event, however,

' that the rlays TR and-CTR are able-to respond to the forward section energy, the controlled signal "Sd will display an indication which is -no more permissive than had the insulated joints 3 at location 13 not failed. The train being'out of the block D-E, no increased hazards to safet are thereby introduced by the 'faulty joint.

Emma-comparison of the equipment "which is represented at location E of Fig. lb with that which has just been describedforlocationD of Fig. -1a,'it will be seen that the broken-down joint protectionfacilities are the same in both instances. The protection facilities shown at location E are, in fact, "all'that will be required to practice our inventionwhen the signal block contains no out .sections and the rails thereof are electrically continuous .from the entrance to the exit end. In such'installations'noline wires are needed between the signal l'locations Ito Feffect the broken-down. joint protection, for by coding the local winding 30 f the protective relay CTR over a "front contact I l of the code following track relay TR the centrifugal device CTR is prevented from being damped during the off code intervals in the same effective manner as were its energizingncircuit to be carried over a line wire to 'theeXit end of-theitrack circuit and there connected in parallel withrthe'track transformer TT, as has been customary in the past.

It 'willbe 'seen,"moreover, that the scheme is 'to circulate through Winding .29 .in the direction applicable .to coded signaling systems of types other than the "frequency code arrangement which has -been disclosed byway .of illustration and that the invention is :not restricted to any particular form of decoding apparatus and ;cir-

.cuits. .Itis, in fact, applicable-to codedsystems of. all types which employ track relays of the :single element .code :followzlng type, such as have been representedat TR in the present drawings.

.The details .of equipment .now typified by trel'ays DRH and :DRziiBO are, therefore, "unimportant as long .as they permit :the protective relays .CTR .to discontinue the usual trackrelay control ithereof when the protective .re'lay becomes :released in response to the reversed polarityenergy which .isreceived .oversa 'iaultyrail joint from therear track section.

Regarding the manner in which the control winding 29 of the lprotecti-ve relay CTRliS connected with the track rails, iithas already been pointed rout that the serial inclusion of this Winding in the .supply circuit for the code .following track relay'TR is-only one of a number "of different ways 'by which this winding :may receiveza measure of the trackway energy which is applied to the code following device'TR. It is, of course, .true that the represented serial connection of the two 5 track relays tends to limit the length of thetrack circuit to, say approximately i500 "to 5000 feet ascompared with around 6000 feet when the .code following re'lay'TR is used alone, yet this :reduction inoperable track circuit length is so comparatively small as not to be greatly objectionable. Besides, the stated limitation may readily-be overcomeby the'use of cut sections of any one of a number of wellknown code repeating types.

In certain cases it may be desirabl to substitute for the previously discussed serial connection of the two ri-ilays TR and :CTR a parallel connectionof their'control windings of the general character which is represented in Fig. 4. Here the=conductors 3 1 and 86 leading from the track rails I and 2 join respectively with conductor-s31 and 35 betweenwhich the control windingof each of the -two relays TR 'and CTR isconnected. As in the case o'f th'e serial connection, normal polarity energy received from the associated track section causes current to flow through Winding 29 in the-direction of fromtleft to right, whilereversedpolarity energy from the rear .tra'ck :section which leaks ever a defective rail joint 33 causes -current to flow through the winding .29 ;in the :opposite direction, or :from right to'left. 'Theiormer causes the relay CTR to pick up its contactspwhileth :latterisrineffective for this purpose and thereby provides the protection against the defective-rail joint inrprecisely the same :manner *as does the before :described serial connection.

It'ha's also beenipointed :outthat the protective'relay TR 'need not'in all instances be of the illustrated "centrifugal frequency selective type. It1may,'for example, be .of the slow release polarized type-which. is represented at C'IRa in .Fig. 5. There the local onexciting winding .30 is constantly energized from the alternating current source B-C,, while'the controlor-track winding 29 is connected t'o receive-energy .from the rails 'l and 2. V

A relay of the type shown .in Fig.5 has no rotating element and obtains its-slowness .of contact release by'meansof 'a dash pot .or'other wellknown expedients. The magnitude of this .release delay "must, as has been indicated ipreviously, be sufficient to span the maximum spacing which occurs between recurrent or consecutive pulses of the coded signal control energy which is received from the trackway during normal operation of the signaling system, and to which the code following device TR is called upon to respond.

When current having an instantaneous relative polarity of the so-called normal variety is circulating through the control (rail-connected) winding of the protective relay CTRa of Fig. 5, the contacts of the relay are moved to their illustrated picked-up positions. When, however, the control winding receives current of reverse polarity, the interaction with the local winding 30 is reversed and the contacts then are forced downwardly into their released positions. In this manner, it will be seen that the modified form of relay shown at CTRa in Fig. is capable of effecting protection against the broken-down rail joints in precisely the sam manner as is the previously described centrifugal type of relay shown at CTR in the earlier figures.

A further advantage of the herein disclosed scheme of our invention is that it is capable of extending the broken-down joint protection to all highway crossing signals which are within the limits of each of the main signal blocks of the automatic wayside system. In the case of the single main block DE of the composite diagram of Fig. la-b, such a highway crossing signal is shown at XS in association with each of the two out locations Da and Db which respectively are occasioned by the two intersecting highways 6 and 1.

Each of these crossing signals XS is controlled by an operation governing relay XR which when energized holds a contact 42 picked up and thereby maintains the signal inactive. When, however, this contact 42 is released, it completes for the signal XS an operating circuit which may be traced from the positive terminal of a suitable supply source through back contact 42, a conductor 43, the operating mechanism (not shown in a detail) of the crossing signal XS and back to the negative terminal of the supply source.

Normally, relay XR receives energizing current over a circuit which is controlled by the equipment which is installed at the entrance end of the track section over which railway trafiic normally approaches the intersection that the signal XS guards. In the case of both of the crossing signals which are represented, this control relay circuit extends from the positive terminal of a suitable supply source through a front contact 44 of the broken-down joint protective relay CTR, conductor 45, a front contact 46 of aslow release relay FP, a line conductor 41 and the winding of relay XR back to the negative terminal of the supply source. I

The just mentioned device. FF is a front contact repeater for the track relay TR and is provided with an energizing circuit which includes a front contact I3 of that code following device. Each time that this contact picks up in response to a pulse of trackway energy being received by relay TR, the winding of relay FP is energized over a circuit which may be traced from the positive terminal of a suitable supply source through front contact [3, conductor 49 and the winding of relay FP back to the negative terminal of the supply source.

As already indicated, relay FF is a slow releasing device and the magnitude of its release delay is sufficiently long that it keeps its contacts continuously picked up between adjacent pulses of trackway energy which the code following relay TR receives during normal operation of the signaling system. This delay is preferably provided through the use of a snubbing resistor 50 bridged across the relay winding and serving to sustain the flux in the magnetic circuit of the relay for an appreciable period following each interruption of winding energizing current.

As long as the track relay TR follows either of the two codes which the transmitter CT at the exit end of the signal block produces, relay FP is held continuously picked up and its contact 46 connects conductor 45 with conductor 41. Under the same conditions, the protective relay CTR also is picked up and its contact 44 completes the energizing circuit for control relay XR at out location Da and thereby maintains the associated highway crossing signal XS inactive. The conditions just described are, of course, in effect as long as the approach section DDa remains unoccupied during normal operation of the signaling system. The same is true of the crossing signal XS which is installed at the second cut location Db.

As will be evident from an inspection of the composite diagram of Figs. 1ab, the relays FF and CTR which govern the control relay for this second signal XS at location Db are installed at the entrance end Da of the track section over which normal direction railway traffic approaches the sec-0nd intersecting highway I. Additionally installed at this entrance location Da (first cut) are facilities for repeating into the rails of the track section to the rear thereof each pulse of coded energy which is received from the rails of the adjoining forward section together with still further means for supplying steady energy to the rear section when there is received from the forward-section either no energy at all or steady energy. 7

The former facilities include a code followin track relay TR which receives operating current from the forward section rails and a track transformer TT which supplies the rear section rails with energy from source B -C each time that relay TR is picked up. The latter facilities further include front contact repeater relay FF and a second or back contact repeater BP for the track relay TR.

Devices TR, CTR and FF at both of the two out locations Da and Db are related to the track circuits and to each other in precisely the same manner as has already been described in connection with location D. That is; the control windings of relays TR and CTR are serially connected between the rails l and 2 of the track section which extends forwardly from their locations; the local winding 30 of relay CTR is supplied from alternating current source B-C with exciting current over a circuit which includes conductor 38 and which is completed each time that contact I I of relay TR is picked up; and the slow release relay FP receives energization over a direct current circuit which includes conductor 49 and which is completed each time that contact l3 of relay TR is picked up.

Regarding the back contact repeater relay BP, its energizing circuit is completed each time that contact [3 of relay TR releases provided a contact v52 of relay FF is at the time picked up. Under such conditions, the circuit may be traced from the positive supply terminal through back contact l3, conductor 53, front contact 52 of relay FP, conductor Stand. the winding; of relay 3? back to the negative supply terminal.

Like relay FP', the second repeater relay ER is sufficiently slow releasing that it keeps its contacts continuously picked up between adjacent pulses of. trackway energy to which the track relay TR responds during normal operation of the signaling system. Preferably, this release delay is provided through the use of a snubbing resistor 5'5 bridged across. the relay winding. In order that this resistor will be eliective only when a companion relay is picked up, the snubbing circuit in which it is included is carried over contact 52 of relay FP. This: assures that each release of relay B? will befol'l'owed almost immediately by a release of relay BP, the delayed release characteristics of. the latter relay being effective only when relay HP is picked up.

In operation. of the energy repeating facilities shown at out section locationDa, relay TR follows the coding of the energy which is received from the forward track section and thus causes both of the repeater relays FF and B? to remain picked up as long as this code following operation takes place. Each time now that relay TR picks up in response to a pulse of forward circuit energy, the rails to the rear of location Da receive a pulse of trackway energy from the transformer TT; this results from contact H of relay TR completing for the primary of transformer TT an energizing circuit which extends from terminal B of the alternating current source through front contact ll, conductors 51 and 26 and the primary of transformer TT back to terminal C of the alternating current source. Likewise each time that relay TR releases its contacts this supply of energy to the rear circuit is discontinued. In this manner the trackway code is repeated around the insulated joints: 3 which define the first cut Da in the main signal block.

In the case, however, that no energy is received from the forward section, theapparatus at location Do then supplies steady energy to the rails of the rear section over a circuit which is completed by a back contact 58 of relay BP and which may be traced from terminal B through back contact 63, conductor 26 and the primary of transformer TT back :to supply terminal C. This results from track relay TR being continuously released and allowing repeater relays FF and BP also to release.

At the second cut location Db in the main signal block D-E, the energy repeating apparatus is arranged in a slightly different manner than at the first location Da. The back contact repeater relay 3? is dispensed with and the supply circuit for the track transformer T1 is completed over the back point of contact ll of the code following track relay TR. This arrangement is known as back contact coding and it so operates that each ofi period of the code which is received from the forward section rails produces an on period in the code repeated into the rear section rails by virtue of contact ll of relay TR completing for transformer TT an energizing circuit which may be traced from supply terminal B through back contact I, conductor 26 and the primary of transformer TT back to supply terminal C. Moreover, this same circuit assures that an absence of energy in the entrance end of the forward track circuit will cause the steady energy to be supplied to the rails of the rear track section.

The manner in which. the highway crossing signals XS at the two out locations Da and Db are controlled and; protected against the giving of false clear indications due to broken-down rail joints will now be considered. As long as the main signal block DE remains vacant both of these signals are maintained inactive. In the case of device XS at the first cut location Da this inactivity results from relays CTR and FF at location D being held picked up by the coded energy which is received. at that location and completinggthe energizing circuit for the crossing signal control relay XR. In the case of device XS at the second cut location Db the named inactivity similarly results from relays CTR and PP at location. Da being held picked up by coded energy which is received from the rails of section Da;-Db.

In the event that a train traveling from left to right enters the section of which location D marks the entrance, the shunting action of its wheels and axles deenergizesrelays TR, CTR and effects the release of relay Fl? at the locationD. Relay FP' releases relatively soon after the entry of the train and breaks at contact 56 the energizing circuit for relay XR which, in turn, completes the operating circuit for; the crossing. signal X5 and brings'this signal into operation thereby warning the users of highway 6 that a train is approaching. Later; contact 44 of relay CTR releases and additionally interrupts the supply circuit for relay XR.

As the front of the train passes the first cut location Do and enters the next succeeding track sectionin advance, the shunting action now effective in: the rails of that section deenergizes relays TR and CTR at location Da and eiTects the release of repeater relays FF and BP at the same location. Contact 46 of relay FP' causes relay XR at the second cut location Db to bring the highway crossing signal XS into action and warn the users of. highway I that a train is approaching. At. the same time contact 58. of relay BP connects transformer TT directly across the supply terminals B and C and thereby causes steady energy to be transmitted to the rails of the rear section D--Da.

As soon as. the rear of the train clears location Da this steady energy is transmitted to the entrance end D- of the rear section and there it holds relay TR continuously picked up which, in turn, causes relays FF and CTR also to-pick up. Contacts 44 and-=16 of these devices now complete for rel ay XR at location Da an energizing circuit which picks up contact 42 and thereby discontinues operation of the first highway crossing signal XS. Meanwhile, both of the decoding relays DRH and DEA-80 at location D remain released and thereby hold the controlled wayside signal Sd at stop.

At location Db the second highway crossing signal XS continues in operation until the rear of the forwardly moving train has cleared location Db. At that time the rails of the central section DaDb become effective for transmitting to the entrance end of that section the steady energy which they receive from the exit end transformer TT over the back point of constantly released contact if of track relay TR at location Db. This, in turn, holds relay TR at location Do. continuously' picked up and causes contacts 44 and 46 of relays CTR and FP at the same location to complete for relay XR at location Db an energizing circuit which picks up contact 42'of that relay and thereby discontinues operation of the second highway crossing signal XS. I

Meanwhile, steady energy continues to be supplied to the rails of the rear section D-Da as a result ofcontact ll of relay TR at location Do connecting the track. transformer TT' at that location directly across the supply terminals B and C. This causes the wayside signal Sd to continue its display of the stop or red indication. Sucha display, moreover, persists under normal operating conditions of the signaling system until the rear of the train clears the exit end of the main signal block When that happens, the rails of section DbE once more become efiective for transmitting energy coded by contact 80 of device CT at the exit location rearwardly to the entrance location Db,

there that 80 coded energy is repeated around the insulated joints 3 and into the rails of the central section Dw-Db by which it is transmitted to the entrance end Da. There it is again repeated around the joints 3 and into the rails of the rear section DDa. In being received at the entrance D of the main signal block, it acts upon code following track relay TR and causes decoding relay DRI-I only to pick up and thereby shifts the signal indication on the part of the wayside signal Sd from stop to yellow or approach. Meanwhile, both of the crossing signals XS at the two locations Da andDb continue inactive because of relays CTR and FF at each of the locations D and Da remaining picked up under the influence of the coded energy.

In addition to preventing the controlled wayside signalSd from displaying a false proceed indication in the eventthat one of the insulated joints 3 fails at location D, the protection facilities which we have illustrated at thislocation also are effective to safeguard the highway crossing signal XS at location Da from remaining inactive in the event of such a joint failure. The later protection comesabout in the following-manner.

The release'of auxiliary track relay CTR which accompanies a leakage of reversed polarity energy over the defective joint from the rear section into the forward section rails interrupts at contact 44 the circuit for relay XR and thereby insures that signal XS will continue in operation as long as any part of a train passing through section D-Da remains within that section. Without" this protective precaution'it will be seen that as soon as the rear of a train advances some distance beyond the entrance location D'where a'brokendown joint has developed, the response of the track relay TR to the rear section leakage energy would be effective to pick up the repeater relay FF and by completing at contact 46 the circuit for relay XR discontinue operation of signal XS even though the train were still within the approach section D-Da.

By falsely indicating to the users of highway'fi that the intersection might safely be entered the premature inactivity 'of signal XS just described would be highly hazardous in that it would lure highway users directly into the pathof the approaching train. As has been seen, the protective expedients of our invention eliminate this hazard and assure that the crossing signal XS will continue in operation for the required length of time even though a failure of the insulated rail joints 3 does occur at the entrance'of the approach section.

Similar protection is provided for the'second crossing signal XS at location'Db. 'In this case the hazard guarded against isthat which would be created should one of the joints 3 at location Do fail and thereby allow energy from the rear section DDa to leak forwardlyinto the rails of the central section Dar-Db. Under that condition, the auxiliary track relay CTR would release and thereby break at contact 44 the circuit for relay XR. This break,'of course, makes it impossible for any subsequent picking up of contact 46 5 .of relay FP to discontinue operation of the signal XS at location Db.

The protective expedients which wehave just described may also be used in situations where the highway crossing signal is responsive to the aplo proach of a train from either direction. Typically, such'a two direction control scheme makes use of a double unit interlocked relayof the type represented at location Db as comprising devices XRiandXRZ. H V Unit XRI corresponds in all respects torelay XR already described in detail in connection with [tacts releases the other contact is prevented from releasing until the first is again picked up and also not until after the windingof the second'relay unit has again been energized. j I 1 As long as the two sections of track which ad- :3 join at location Db' remain vacant, the relays I CTR and FF at both of the locations Daand Db are maintained picked up, both of the windings XRI and XRZ of the interlocking relays are energized and the highway crossing signal XS is @3 maintained inactive by virtue ofboth of; the contacts 42 and 42a being picked up. If a train moving in the forward direction of from-lefttoaright enters section Da-Db relays CTR and FPat location Da release and unit XRI of the interlock- =40 nig relay drops contact 42 to bring the signal XS into operation at locationDb;

As the train advancesinto section DbE relays CTR and F? at location Db also release and deenergize the winding of interlocking relay unit F45 XR2. Contact 42a does not, however, release due to the action of the before'described interlocking mechanism. Accordingly, when the rear of 'the train clears location Db, highway crossing signal XS ceases to operate as the result of contact-r42 of relay XRI being picked up. The original interlock of contact 4211 persists until the winding of unit XR2 is again energized and this doesinot happen until the rear of the train clears the exit end Evof the forward section. i

If a train traveling in the reverse direction of from right to left enters the approach section DbE, the crossing signal XS at location Db will again be brought into operation as a result of contact 42a releasing inv response tothe deenergization of winding XRZ which is effected by the release. of contacts 44a and 46a of relays CTR and FF at location Db. Thisrelease, of course, accompanies the deenergization-of the track relay TR which is produced by the rail shunting? action of the train wheels and axles. As the train advances into section DbDa, it similarly Vefiects once more ceases as the result of, contact 4211 be- 178 ing picked up in response to the energization of relays CTR and FF at location Db. The original interlock of contact 42 continues until the rear of the departing train clears location Da.

From the foregoing it will be seen that in the case of the forwardly moving train the signal XS at intersection Db is protected from premature inaction upon failure of a rail joint 3 at location Da in the same manner as that already described in connection with the crossing control system using the single unit governing relay XR. Likewise, it will be seen that in the case of the reverse moving train the same crossing signal XS at intersection Db is similarly protected in the event that one of the rail joints 3 at location Db should fail while a train is within the section DbE.

In the latter situation the tendency would be for the energy from section Du -Db to leak over the faulty joint and operate relay TB in such manner as to keep the signal XS at intersection Db inactive until the reverse running train had approached very close to the intersection. With the scheme which we have represented, however, relay CTR at location Db does not respond to the leakage energy and thus it opens at contact Ma the energizing circuit for interlocking unit XR2 as soon as the train enters section Db--E and in this manner the desired control of the crossing signals is at all times assured.

Referring now to Fig. 3, we have there represented one manner in which our improved circuits may be arranged in case it is desired to provide the crossing signal XS at intersection Dc with a two direction control scheme of the type just described in connection with the crossing signal at intersection Db. It will be noted from Fig. 3 that unit XRI of the interlocking relay replaces the single unit re lay XRrnow shown in Fig. 1a, and that the unit XRZ is connected in a manner which is identical with the connections of the corresponding unit now shown at location Db in Fig. 1b. In addition to the contacts 44 and 46 which control the crossing signal at the advance cut location Db, the relays CTR and FF at location Da are provided with the contacts Da and 46a which are arranged in the manner shown.

In view of the complete description of the two direction running system which has already been given, it is thought that the manner of operation of the extended circuits of Fig, 3 will be fully apparent.

Reverting to certain more general features of the broken-down rail joint detective scheme of our invention, theuse of the centrifugal frequency selective type of relay which is represented at CTR is especially desirable in applica tions that'employ direct current track relays TR which receive pick-up energy through resonant rectifier units of the character represented at 9 in Fig. 1 and shown in greater detail in Fig. 2.

- Should, for any reason, this unit fail to keep out of the 25 cycle per second propulsion energy, the code following track relay TR. will, of course, be energized continuously. In so far as the Wayside signals S are concerned, such failure would not introduce any hazard to safety for the reason that the failure of the track relay TR. to follow code will cause the controlled wayside signal to go to stop and there continuously remain.

In the case of the highway crossing signals XS, however, a failure of the type described in the preceding paragraph would, in the absenceof the special protectiverelays CTR herein disclosed, pick up repeated relay FP and thereby maintain the crossing signal XS at the cut section in advance inactive even though a train might be in the section of track which interconnects the Wayside signal location (such as D in Fig. 1a) with the cut section (such as Da in Fig. 1a) where the crossing signal XS is positioned. It will be noted, however, that the centrifugal frequency selective relay CTR efiectively prevents this hazardous possibility due to the fact that it is unable to re spond to the low or 25 cycle propulsion energy which may reach the control winding 29 thereof. Such failure to respond is due to the fact'that the local winding is excited by 100 cycle per second energyand to the further fact that even were this exciting winding also to receive 25 cycle energy the speed of rotation of the fly ball mechanism 3! which would result still would be far toolow to raise the contacts 33 and 44 to their picked-up positions. Contact 44 thus remaining open, the crossing signal XS would be continued in action.

In all of the applications which we have disclosed herein, moreover, should the insulated rail joints break down when the affected sections 'of track are vacant, the polarity selective characteristics of the protective relay CTR will in each instance cause that relay to release when winding 29 thereof receives the reverse polarity energy which leaks over the faulty joints from the rear track section into the track section ahead. In the case of the wayside signals S, as has been seen, contact '33 now assures the stop indication by rendering inactive the decoding apparatus (relays DRI-I and DRlfill), while in the case of the highway crossing signals XS contact 44 assures that a warning will be continued' as long as needed. The functions just named'cannot, 'of course, be performed by a single element track relay of the type shown at TR for the reason that such a relay is not selective as to polarity. To make it such, moreover, and yet retain its code following characteristics would greatly complicate its design, substantially add to its' cost,- and minimize the reliability of its operationl Hence, the special utility of the scheme which we have herein disclosed as utilizing a supplemental protectiverelay CTR.

From the foregoing it will be seen that we have provided new and improved forms of organization of railway traflic controlling apparatus into signaling systems wherein coded energy normally is supplied to the track circuits for the purpose of controlling either or both wayside signals and train carried cab signals and in which code following track relays of the single element type are utilized; All of these organizations are efiective to detect the failure'of the insulated joints which electrically separate the rails of adjacent track sections and in the event of such failure to prevent'the controlled wayside signals from giving false proceed indications, and to continue'highway crossing signals in operation as long as a'warning therefrom is needed to advise. highway users of an approaching train. This protection is effected without the necessity for line wires interconnecting the opposite ends of automatic signalblocks and it may readily be extendedto allhighway crossing signals which are within the limits of each of those blocks. All of the above,. moreover, has been accomplished without dispensing with any of the desirable features ofcontinuously coded track circuits.

though we have herein shown and described only a few of the many possible forms of railway periodically interrupted energy of a given polarity, a code following track relay connected to receive operating energy from said rails, a signal so controlled by said track relay as to give a non-restrictive aspect when the track relay is responding to said periodically interrupted energy and a danger aspect when the track relay is continuously released, means for supplying the rails of said rear section with energy having a polarity which is opposite to that of said forward section energy, a slow-release auxiliary relay connected in energy receiving relation with said forward section rails and arranged to pick up only in response to received energy which has said given polarity and to release should opposite polarity energy or no energy at all be received, and means governed by said auxiliary relay for causing said signal also to .give said danger aspect whenever the auxiliary relay is released whereby to assure that said signal will provide a warning indication in the event that said insulated rail joints should break down and transmit said opposite polarity energy from the rear track section into the forward track section.

2. In combination with adjoining forward and rear sections of railway track whichv are electrically separated by insulated rail joints, means for supplying periodically interrupted energy of a given polarity to the rails of said forward section, a code following track relay connected to receive operating energy from said rails, a signal so controlled by said trackrelay as to givea non-restrictive aspect when the track relay is responding to said periodically interrupted energy and a danger aspect when the track relay is continuously released, means for supplying the rails of said rear section with periodically interrupted energy having a polarity which is opposite to that of said forward section energy, an auxiliary relay connected to receive energy from said forward section rails and arranged to pick up when said received energy has said given polarity and there continuously stays even though that energy is periodically interrupted and to release should opposite polarity energy or no energy at all be received, and means governed by said auxiliary relay for causing said signal also to give said danger aspect whenever the auxiliary relayis released whereby to assure that that signal will provide a warning indication in the event that said opposite polarity energy should feed over said insulated rail joints from the rear track section into the forward track section. o. v, v

3. In combination with adjoining forward and rear sections of railway track which are electrically separated by insulated rail joints, means for supplying periodically interrupted energy of a given polarity to the rails of said forward section, a code following track relay connected to receive operating energy frorn said'rails, asignal so controlled by said track relay asjto give a non-restrictive aspect when the track relay is responding to said periodically interrupted energy and a danger aspect when the track relay is continuously released, means for supplying the rails of said rear section with periodically interrupted energy having a polarity which is opposite to that of said forward section energy, an auxiliary relay of the centrifugal type provided with a control winding connected in energy receiving relation with said forward section rails and also having an exciting winding, means controlled by said track relay for impressing given polarity energy upon said exciting winding each time that the track relay is energized whereby to cause said auxiliary relay to pick up and there stay continuously when said periodically interrupted energy of said given polarity is received by said control winding from the forward section rails and to release should opposite polarity energy or no energy at all be received, and means governed by said auxiliary relay for also causing said signal to display said danger aspect whenever the auxiliary relay is released whereby to assure that that signal will give a warning indication in the event that said opposite polarity energy should feed over said insulated rail joints from the rear track section into the forward energy and a danger aspect when the track relay is continuously released, means for supplying the rails of said rear section with periodically interrupted energy having a polarity which is opposite to that of said forward section energy, an

auxiliary relay having a control winding which is serially included in said track relay supply circuit and which also receives energy from said forward section rails, said auxiliary relay being arranged to pick up when said received energy is .of said given polarity and there continuously stay even though that energy'is periodically interrupted and to release should opposite polarity energy or no energy at all be received, and means governed by said auxiliary relay for causing said signal also to display said danger aspect whenever the auxiliary relay releases as in response to opposite polarity energy leaking over said insulated rail joints.

;5. In combination with adjoining forward and rear sections of railway track which are electrically separated by insulated rail joints, means for supplying periodically interrupted energy of a given polarity to the rails of said forward section, a code following track relay, a supply circuit connecting the winding of said track relay across said forward section rails whereby that relay receives operating energy from those rails, a signal so controlled by said track relay as to give a non-restrictive aspect when the track rclay is responding tosaid periodically interrupted energy and a danger aspect when the track relay 'is continuously released, means for supplying the rails of said rear section with periodically interrupted energy having a polarity which is opposite to that of said forward section energy,

vided with a control winding which is serially included in said track relay supply circuit and also having an exciting winding, means controlled by said track relay for impressing given polarity energy upon said exciting winding each time that the track relay is energized whereby to cause said auxiliary relay to pick up and there stay continuously when said periodically interrupted energy of said given polarity is received by said control winding from the forward section rails and to release should opposite polarity energy or no energy at all be received, and means governed by said auxiliary relay for also causing said signal to display said danger aspect whenever the auxiliary relay is released as in response to opposite polarity energy leaking over said insulated rail joints.

6. In combination with adjoining forward and rear sections of railway track which are electrically separated by insulated rail joints, means for supplying periodically interrupted energy of a given polarity to the rails of said forward section, a code following track relay, a supply circuit connecting the winding of said track relay across said forward section rails whereby that relay receives operating energy from those rails, a signal so controlled by said track relay as to give anon-restrictive aspect when the track relay is responding to said periodically interrupted energy and a danger aspect when the track relay is continuously released, means for supplying the rails of said rear section with periodically interrupted energy having a polarity which is opposite to that of said forward section energy, an auxiliary relay having a control winding which is connected in parallel with said track relay winding whereby also to receive energy from said forward section rails, said auxiliary relay being arranged to pick up when said received energy is of said given polarity and there continuously stay even though that energy is periodically interrupted and to release should opposite polarity energy or no energy at all be received, and means governed by said auxiliary relay for also causing said signal to display said danger aspect whenever the auxiliary relay is released as in response to opposite polarity energy leaking over said rail joints.

'7. In combination with adjoining forward and rear sections of railway track which are electrically separated by insulated rail joints, means for supplying the rails of said forward section with periodically interrupted energy of a given polarity, a code following track relay connected to receive operating energy from said rails, a wayside signal positioned at the entrance of said forward section and so controlled by said track relay as to give a permissive aspect when the track relay is responding to said periodically interrupted energy and a stop aspect when the track relay continuously occupies either the picked up or the released position, means for supplying the rails of said rear section with periodically interrupted energy having a polarity which is opposite to that of said forward section energy, an auxiliary relay connected to receive energy from said forward section rails and arranged to pick up when said received energy has said given polarity and there continuously stay even though that energy is periodically interrupted and to release should opposite polarity energy or .no energy at all be received, and means governed by said auxiliary relay for causing said signal also to show stop whenever the auxan auxiliary relay of the centrifugal type proiliary relay is reieased whereby to assure that that signal will give a warning indication in the event that said opposite polarity energy should feed over said insulated rail joints from the rear track section into the forward track section.

8. In combination with adjoining forward and rear sections of railway track, means for supplying the rails of said forward section with periodically interrupted energy of a given polarity, a code following track relay operated by energy received from said rails, a decoding transformer, a source of unidirectional exciting current therefor, an exciting circuit by way of which said transformer is connected with said source over a contact of said track relay, a signal positioned at the entrance of said forward section and so controlled by the output energy of said decoding transformer as to give a permissive indication when said track relay is responding to said periodically interrupted energy and to show stop either when that relay fails to follow code or when the decoding transformer is continuously disconnected from its said exciting source, means for supplying the rails of said rear section with periodically interrupted energy of a polarity vhichis opposite to that of said forward section energy, an auxiliary relay connected to receive energy from said forward section rails and arranged to pick up when said energy has said given polarity and there continuously stay even though that energy is periodically interrupted and to release should opposite polarity energy or no energy at all be received, and means governed by said auxiliary relay for disconnecting said transformer from said exciting source whenever the auxiliary relay is released whereby to cause said signal also to give said stop indication in the event that said opposite polarity energy should leak from the rear track section into the forward track section.

9. In combination with adjoining forward and rear sectionsof railway track, means for supplying the rails of said forward section with periodically interrupted energy of a given polarity, a code following track relay operated by energy received from said rails, decoding means including a transformer and a source of exciting current connected with the transformer over a pole changing contact of said track relay, a signal positioned at the entrance of said forward section and so controlled by said decoding means as to give a permissive indication when said track relay pole changes the exciting current for said transformer and to show stop when the track relay fails to follow code .or when the transformer is disconnected from said exciting source, means for supplying the rails of said rear section with energy having a polarity which is opposite to that of said forward section energy, a slow release auxiliary relay receiving energy from said forward section rails and arranged to pick up when that received energy is of said given polarity and to release should opposite polarity energy or no energy at all be received, and means governed by said auxiliary relay for disconnecting said transformer from said exciting source whenever the auxiliary relay is released whereby to cause said signal also to give said stop indication in the event that said opposite polarity energy should leak from the rear track section into the forward track section.

10. In combination with adjoining forward and rear sections of railway track, means for supplying the rails of said forward section with periodically interrupted energy of a given polarity, energy received from said rails, a decoding transformer, a source of unidirectional exciting cur-- rent therefor, an exciting'circuit by way of which said transformer is connected with said source over a contact of said track relay, a signal positioned at the entrance of said forward section and so controlled by the'output energy of said decoding transformer as to give a permissive indication when said track relay isresponding to said periodically interrupted energy and to show stop either when that relay fails to follow code or when the decoding transformer is continuously disconnected from. its said exciting source, means for supplying the rails. of said rear section with periodically interrupted energy of a polarity which is opposite to that of said forward section energy, a slow release auxiliary relay receiving energy from said forward section rails and arranged to pick up when that received energy is of said given polarity and to release should opposite. polarity energy or no energy at all be received, and afront contact of said auxiliary relay included in the said exciting circuit of said decoding transformer for the purpose of continuously disconnecting that transformer from its said exciting source should energy of said opposite polarity be transmitted into the forward section rails;

11. In combination with adjoining forward and rear sections, of railway track which are electrically separated by insulated rail joints, means for supplying the rails of said forward section with energy which hasa given polarity Q and which is periodically interrupted under certain conditions and steady under others, a code following track relay connected to receive operating energy from said rails, a highway crossing.

signal at the exit end of said forward section, 40 means. governed by said track relay for maintaining said crossing signal inactive when the track relay eitheris responding to said periodically interrupted energy or is continuously picked up and for placing that signal in operation when the track relay is continuously released, means for supplying the rails of said rear section with periodically interrupted energy having a polarity which is opposite to that of said forward section energy, a slow release auxiliary 5g relay connected in energy receiving relation with said forward section rails and arranged to pick up only in response to received energy which has said given polarity and to release should opposite polarity energy or no energy at all be received, 5.1 and means governed by said auxiliary relay for also placing said crossing signal in operation whenever the auxiliary relay is released whereby to assure that a warning indication will be given by that signal in the event that said insulated ,9 rail joints should break down and transmit said opposite polarity energy from the rear track section into the forward track section.

12. Incombination with adjoining forward and rear sections of railway track which are elec- 5 trically separated by insulated rail joints, means for supplying the rails of said forward section with energy which has a given polarity and which is periodically interrupted under certain conditions and steady under others, a code followin 70 track relay connected to receive operating energy from said rails, a highway crossing signal at the exit end of said forward section, means governed by said track relay for maintaining said crossing signal inactive when the track relay 7;; either is responding to said periodically intera code following track relayoperat'ed by rupted 'energy'or is continuously picked up and for placing that signal in operation when the track relay is continuously released, means for supplying the rails'of said rear section with periodically interrupted energy having a polarity which is opposite to that of said forward section energy, an auxiliary relay also connected to receive energy from said forward section rails and arranged topick up when said received perry is of said given polarity and in either. said Peri-- odically interrupted or said steady form andvt'o release should opposite polarity energy orfno energy at all be received, and means -governed by said auxiliary relay for also placing said crossing signal in operation whenever the auxiliary relay is released whereby to assure that a warning indication will be given by that signal in the event that said opposite polarity energy should feed over said insulated rail joints from the rear track section into the forward track section.

13. In combination with adjoining forward and rear sections of railway track, means for supplying the rails of said forward section with energy which has a given polarity and which is periodically interrupted under certain conditions and steady under others, a code following track relay said rails, a slow release repeater relay energized over a front contact of said track relay and arranged to pick up when the track relay either is responding to said periodically interrupted energy or is continuously picked up and to release when the track relay is continuously released, a highway crossing signal controlled by said repeater relay and arranged to be maintained inactive when the repeater relay is picked up and to be placed in operation when the repeater relay is released, means for supplying the rails of said rear section with periodically interrupted energy having a polarity which is oppo site to that of said forward section energy, an auxiliary relay also connected to receive energy from said forward section rails and arranged to pick up when said received energy is of said given polarity and in either said periodically interrupted or said steady form and to release should opposite polarity energy or no energy at all be received, and means including a contact of said auxiliary relay for also placing said crossing signal in operation whenever the auxiliary relay is released.

14. In combination with adjoining forward and rear sections of railway track, means for supplying the rails of said forward section with energy having a given polarity and which is periodically interrupted under certain conditions and steady under others, a code following track relay connected to receive operating energy from said rails, a slow release repeater relay energized over a front contact of said track relay and arranged to pick up when the track relay either is responding to said periodically interrupted energy or is continuously picked up and to release when the track relay is continuously released, a highway crossing signal, a relay for controlling the operation of said signal arranged to maintain the signal inactive when picked up and to place the signal in operation when released, an energizing circuit for said signal control relay which includes a front contact of said repeater relay whereby said signal comes into operation when the repeater relay is released, means for supplying the rails of said rear section with periodically interrupted energy having a polarity which is opposite to that of said forward section energy,

connected to receive operating energy from an auxiliary relay also connected to receive energy from said forward section rails and arranged to pick up when said received energy is of said given polarity and in either said periodically interrupted or said steady form and to release should opposite polarity energy or no energy at all be received, and a front contact of said auxiliary relay serially included in the said energizing circuit for said signal control relay whereby to cause said signal also to be brought into operation whenever the auxiliary relay is released.

15, In combination with adjoining forward and rear sections of railway track, means for supplying the rails of said forward section with energy which has a given polarity and which is periodically interrupted under certain conditions and steady under others, a code following track relay operated by energy received from said rails, a first slow release relay energized when said track relay is picked up, a second slow release relay energized when said track relay is released provided said first slow release relay is picked up, a source of energy for the rails of said rear track section having a polarity which is. opposite to that of said forward section energy, a circuit controlled by said tra ck relay for connecting said source to said rear section rails each time that the track relay is picked up whereby periodically interrupted energy received from the forward section rails will cause periodically interrupted energy of opposite polarity to be supplied to those rear section rails, another circuit controlled by said second slow release relay for also connecting said source to said rear section rails whenever the second slow release relay is released whereby either steady energy or no energy at all received from the forward section rails will cause steady energy of opposite polarity to be supplied to those rear section rails, a highway crossing signal controlled by said first slow release relay and arranged to be maintained inactive when the first slow release relay is picked up and to be placed in operation when that relay is released, an auxiliary relay also connected to receive energy from said forward section rails and arranged to pick up when said received energy is of said given polarity and in either said periodically interrupted or said steady form and to release should opposite polarity energy or no energy at all be received, and means governed by said auxiliary relay for also placing said crossing signal in operation whenever the. auxiliary relay is released whereby to assure that that signal will provide.

a warning indication in the event that said opposite polarity energy should leak from the rear track section into the forward track section.

16. In combination with consecutive rear, central and forward sections of railway track, means for supplying the rails of said forward section with periodically interrupted energy of a given polarity, means at the junction of said central and forward sections for supplying the rails of said central section with opposite polarity energy which is periodically interrupted when periodically interrupted energy is received from said forward section rails and which is steady when no energy is received from those forward rails, means at the junction of said rear and central sections including a code following track relay connected with said central section rails for supplying the rails of said rear section with given polarity energy which is periodically interrupted when periodically interrupted energy is received by the relay from said central section rails and which is steady both when steady energy and when no energy at all is received, a highway crossing signal at the exit of said central section so governed by said track relay as to be main- .1

tained inactive when that relay is responding to periodically interrupted energy and to be placed in operation when the track relay is continuously released, a slow release auxiliary relay connected in energy receiving relation with said central section rails and arranged to pick up only in response to received energy which has said opposite polarity and to release should given polarity energy or no energy at all be received, and means governed by said auxiliary relay for also placing said crossing signal in operation whenever the auxiliary relay is released whereby to assure that that signal will provide a warning indication in the event that said given polarity energy should leak from the rear track section into the central track section.

RALPH R. KEMMERER.

CHARLES W. FAILOR. 

